1. Field
An embodiment of the invention relates generally to the field of photography and, more particularly, to a system for automating the focus control of a film or video camera.
2. Background
Maintaining a properly focused image is critically important in film and television productions. This task is complicated by the fact that many shots require a moving object to be kept in focus or require different objects at different distances from the camera to be in focus at different times during the shot. Before a shot, the person responsible for focusing the camera typically prepares for the shot by carefully measuring the distance to each object that is to be in focus during the shot. These distances are then recorded for use during the shot, such as by marking the focusing ring on the camera lens with the measured distances. During the shot, a “focus puller” adjusts the focusing ring to bring each object into precise focus at the desired time. This method obviously relies on the skill of the focus puller. It is difficult enough to maintain proper focus with stationary objects. If the camera or the subjects to be photographed are moving, it becomes even more difficult to maintain the proper focus. Furthermore, this method is time consuming since careful measurements must be taken and recorded before each shot. While this is being done, the cast and the rest of the production crew must often remain idle. There is a need, therefore, for a method and apparatus for automating the camera focusing process.